fix example (client)

[MauroMombelli]

I've found some error in the default example:

Request request

is using object Request that does not exist anymore, and String should be used now.

String response = client.post(request);

send a void SOAPEvent header witch cause a 500 server's error, changing to
String response = client.post("http://www.webserviceX.NET/ConversionRate",request);

fix it.

Fixed example code:
Wsdl wsdl = Wsdl.parse("http://www.webservicex.net/CurrencyConvertor.asmx?WSDL");

    SoapBuilder builder = wsdl.binding()
        .localPart("CurrencyConvertorSoap")
        .find();
    SoapOperation operation = builder.operation()
        .soapAction("http://www.webserviceX.NET/ConversionRate")
        .find();
    String request = builder.buildInputMessage(operation);

    Security s = Security.builder().authBasic("admin", "admin").build();

    SoapClient client = SoapClient.builder()
        .endpointUri("http://www.webservicex.net/CurrencyConvertor.asmx").endpointSecurity(s)
        .build();

    System.out.println(request);

    String response = client.post("http://www.webserviceX.NET/ConversionRate",request);